Engine starter gearing



Sep 3, 1946. J. E; BuxTqu 2,407,132

- ENGINE STARTER GEARING Filed Dec. 29 1944 INVENTOR.

' ATTORNEY Patented Sept. 3, .1946

k ENGINE STARTER GEARING Ja'rnesE. Buxton, Elmira, N. Y., assignor to Bendix AviationCorporation, South ...poration of Delaware Bend, Ind.; a cor- "Application December 29, 1944, Serial No. 570,376 l 1 The present invention relates to engine starter gearing and more particularly 'to' an automatically disconnectable starter drive of the type which is arranged to maintain its engagement with the engine until it is reliably self-operative. Itisan object of the present invention to provide a novel starter drive which is positively held in engagement until the engine is successfully started.

It is a further object to provide such a device in which the release of the holding means takes place quickly and reliably.

It is anotherobject to provide such a device in which a part of the holding means serves also as an anti-drift detent to prevent undesired engagement of the gearing.

Furtherobjects and advantages will be apparent from the following dscription taken in connection with the accompanying drawing in which:

1 Fig. 1 is a side elevation partly in section of a preferred embodiment of the invention;

;.. Fig. Z'is a section-taken substantially on the line 2'--2 of Fig. 1 showing the latching members inreleased position. e

Fig.- 3 is a similar view showing the latching parts in engaged position; I u Fig. 4 he detail'in perspective of the internally threaded driving clutch -member and I Fig. 5 is a detail in perspective of the driven clutch member. v In Fig. 1 of the drawing there is illustrated a power shaft I, and a pinion'2 slidably journalled on the power shaft for movement into and out of engagement with gear 3 of an engine to be started. A sleeve 4 is fixed on the power shaft in any suitable manner as indicated at 5 and is provided with a portion 6 of non-circular cross-section at one end, a cylindrical reduced portion 1 adjacent thereto, and a threaded terminal portion 8 on which is fixedly mounted a stop nut 9.

A driving plate member I is splined on the non-circular portion 6 of the sleeve 4 and is retained thereon by a thrust ring II. A screw shaft I2 is slidably journalled on the cylindrical portion I of the sleeve 4 and is provided with a non-circular portion I3 on which is splined a driven anchor plate I4. A spring I connects the two anchor plates I0 and It by means of outturned ends I6 and H which enter slots in said anchor plates whereby the screw shaft is yieldably connected for both rotary. and longitudinal movement with sleeve 4.

A driving clutch member in the form of a nut I8 is threaded on the screw shaft I2 and has a 5 Claims. (01.74-7) 2 radial flange I9 (Fig. 4) on which are formed dentals 20. Means for connecting the pinion 2 to the driving clutch member I8 is provided com prising a driven clutch member 2I (Fig. 5) hav ing dentals 22 adapted to cooperate with the dentals of the driving clutch member and having radial lugs 23 extending into corresponding openings 24 in a barrel member 25, and retained there in by a lock ring 26. The barrel member 25 is rigidly connected to the pinion as indicated at 21 whereby the pinion and driven clutch member 2| are constrained to move together as a unit. A light compression spring 28 is located between the drivenclutch member 2I and a flange 29 on the stop nut 9 whereby the spring tends to hold the driven clutch member in engagement with the driving clutch'member and also tends to demesh the pinion 2 from the engine gear 3. Means are provided for holding the pinion in engagement with the engine gear in the form of a pair of cooperating latch members 30, and 3I (Fig.- 2) mounted respectively on the driving clutch member I8 and a screw shaft I2. Latch member 30 is slidably mounted in a radial opening 32 in a ring 33 which is fixedly mounted in any suitable way as by brazing or welding on the driving clutch member I9. ranged to yieldingly press the inner end 35 of the latch member 3|] against the screw shaft and thereby cause it to act as an anti-drift member to prevent the pinion from undesired engagement with the engine gear.

The latch member 3| is pivoted at 36 to a cup member 31 which is non-rotatably mounted on the non-circular portion I3of the screw shaft between the anchor plate I4' and a. stop fiange 39. The sliding latch member 30 has an enlarged head 40, and the pivoted latch member 3| has a hook 4| on one end which is formed to engagev the head 40 of the latch member 30 as shown in Fig. 3 to prevent relative rotation between the nut member I8 and th screw shaft I2. The pivoted latch member 3I is provided with a weighted arm 42 which flies out under the influence of centrifugal force so as to bring the hook 4| into the path of the head 40 of latch member 30 when the latter has been moved out by centrifugal force against the action of the spring 34. A spring 43 normally retains the pivoted latch member Si in retracted position as shown in Fig. 2, the inward movement of the weighted arm 42 being limited by a pin 44 which bears on the periphery of the ring 33.

In operation, starting with the parts in the positions illustrated in Fig. 1, rotation of the power shaft I is transmitted through the sleeve 4,

A spring 34 isar-,

anchor plate [0, spring l and anchor plate [4 to the screw shaft l 2.

The driving clutch member I8 is thereby traversed away from idle position which motion is transmitted through the driven clutch member 2| and barrel 25 to the pinion 2 which is thereby moved into mesh with the engine gear 3. When the travel of the clutch members is arrested by the stop nut 9 the resistance to rotation of the pinion causes the spring I 5 to be compressed and torqued until suiiicient force is built up to rotate the engine gear 3.

During the cranking of the engine centrifugal force acts on the sliding latch member 30 to moveit outward, and on the pivoted latch 3| to move the hook 4| inward until they are in position to engage as shown in Fig. 3. When the engine fires, the excess rotation of the pinion from the engine gear is transmitted through the barrel 25 to the clutch members whereby the driving clutch member I8 is caused to back away from the stop nut 9. As soon as this backward movement has progressed sufliciently to release the clutch members. from each other, the head 40 of latch member 30 engages with the hook 4| on latch member 3| as shown in Fig. 3 and prevents further relative rotation between the driving clutch member and screw shaft. The pinion is thereby held in engagement with the engine gear while being permitted to overrun freely by the release of the engagement between the clutch members [3, 2|.

If the engine should not continue self-operative, the driving clutch member again advances into engagement with the stop nut 9 and cranking is resumed. When a successful start has been secured, deenergization of the starting motor by the operator causes the speed of the screw shaft and clutch member l8 to be reduced sufliciently to permit the centrifugal latches to disengage. Inasmuch as this disengagement may be brought about by the retraction of either or both of the latch members, it is obvious that the. release will take place quickly and infallibly when the power shaft slows down below the critical speed. This quick release of the latch is desirable in that it is conducive to a rapid. and. quiet olemeshing' movement of the pinion.

Although but one embodiment of the invention has been shown and described in detail, it will be understood that, other embodiments are possible and various changes may be made in the form and arrangements of the parts without departing from the spirit of the invention as defined in. the claims appended hereto.

What is claimed is:

1. In an engine starter drive, a. power shaft, a

4 pinion slidably journalled thereon for movement into and out of mesh with a gear of an engine to be started, a screw shaft mounted on the power shaft, means connecting the screw shaft to rotate with the power shaft, a nut on the screw shaft, means including a disconnectable clutch for actuating the pinion by the nut, a centrifugal latch member on the nut, a second centrifugal member and means for mounting the second centrifugal member for rotation with the screw shaft in position to cooperate with the latch member and prevent the nut from movement on the screw shaft to demesh the pinion.

2. In an engine starter drive, a power shaft, a pinion slidably journalled thereon for movement into and out of mesh with a gear of an engine to be started, a screw shaft mounted on the power shaft, means connecting the screw shaft to rotate with the power shaft, a nut on the screw shaft, means including a disconnectable clutch for actuating the-pinion by the nut, a radially slidable centrifugal latch member on the nut, a second centrifugal member and means for pivotally mounting the second centrifugal member for rotation with the screw shaft, said second centrifugal member havingv a portion movable by centrifugal force into the path of said slidable latch member so as to prevent the nut from movement on the screw shaft to demesh the pinion.

3. An enginestarter driveas set forth in claim 2 including further spring means normally press ing the sliding latch member into frictional engagement with the screwshaft.

4. In an engine starter drive a power shaft, a pinion slidably journalled thereon for movement into and out of mesh with agear of anengine to be started, a screw shaft on the power shaft, a clutch member in the. form of a nut threaded on the screw shaft, a second clutch member slidably journalled on the nut and rigidly connected to the pinion, yielding means urging the clutchmembers into engagement and tending to move'them in unison in. a direction.- to demesh the pinion, and centrifugal latch means preventing demeshing movement of the pinion while the nut is rotated above a predetermined speed.

5.. An. engine starter drive asset forth in claim 4 in which said centrifugal latchv means includes two elements movable in opposite directions by centrifugal force so as to engage and prevent relative movement of the nut and screw shaft in a direction to demesh the pinion while they are rotating above a predetermined speed.

JAMES E. BUXTON. 

